Various developer additives are known and employed in the field of photographic processing to produce clearly defined, high contrast images exhibiting improved halftone dot quality. The practice is particularly well known in the graphic arts industry.
Dot quality is characterized by halftone dots having high density and well defined image sharpness. In determining dot quality the processed samples are evaluated through microscopic observations and rated subjectively on a numerical scale from 1 to 4 of diminishing quality wherein 1.0 is excellent and 4.0 is unacceptably poor.
In order to produce the desired halftone dot quality and good gradient for sharp image formation, it is necessary that a suitable developer be used with an appropriate photosensitive material. Many modifications of the developer compositions have been made for these purposes. For example, linear polyethylene glycols have been added to developers to reduce the induction period. Also it is known to use linear polyalkylene glycols or alkylene oxide polymers in a hydroquinone or substituted hydroquinone developer having low ionized sulfite to produce good dot quality and increased gradient.
It has now been found that cyclic polyethers or crown compounds are more effective for increasing gradient and improving dot quality in lithographic films than the linear polyethers. Films processed in these developer compositions give excellent dot quality at optimum development times, as well as latitude in terms of gradient.